the process of natural selection


the process of natural selection

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Animal A is unsuited for its environment and dies of exposure/starvation/heat stroke/whatever. Animal B is well suited to its environment and survives long enough to fuck. Animal B is going to have little copies of it running around, A doesn’t.

Note that “fitness” for evolution isn’t the same as “fitness” for Planet Fitness. Animal A could be some muscular gigachad that’s faster, deadlier, smarter and sexier than Animal B. If it finds itself in an environment that has scarce food (say, a desert), all those extras will have a huge extra energy draw and it will starve to death while the scrawny little Animal B who happens to be *very* efficient at living off of two bites of cactus and a random moth per day will have no trouble.

Natural selection is a process where animals or plants with helpful traits (like being able to run faster or having stronger beaks) are more likely to survive and have babies. These helpful traits get passed down to their babies, so over time, more and more animals or plants in a population have these helpful traits. This process helps animals and plants adapt to their environment and can lead to new species.

Every individual member of a species varies a little bit from every other member. It might be the length of a bird’s beak, the length a grashopper’s leg, the colour of a marmot’s fur, etc.

If any of these animals lives long enough to reproduce, then their offspring will share at least some of these characteristics.

Given the organism’s habitat, if a variation makes it far more likely for that individual to reproduce, then it is more likely that this trait will carry on. Likewise, if a trait inpede’s an individual’s ability to reproduce, then it is likely that this trait will end with that individual.

A great example might be bird beaks. Beaks of a certain species of bird might come in various lengths. If the habitat includes a food source such as seeds held in a pod that only longer beaked birds can reach, then these birds now have an extra food source that short beaked birds do not. This alone might not cause long beaked birds to prevail over short beaked birds.

But if some calamity were to wipe out most food sources except for this particular kind of seed pod, then most of the short beaked birds will starve out and eventually stop reproducing. Since the long beaked birds can still find food, they can reproduce in sufficient numbers to sustain a populatuon of long beaked birds, while their short beaked cousins to go extinct.

Over hundreds of thousands of years, the net result is the apparently specialized biodiversity we observe today.

Imagine there is a forest that’s all green. There are bugs in this forest of all kinds of colors, and birds that eat the bugs, picking them out from the green background.

The greener a bug is, the less likely a bird will eat it. These bugs will lay eggs for the next generation of bugs, which will be more likely to be green for the genes that made the original bugs green as well.

Over many years, the forest becomes full of green bugs that the birds have difficulty spotting. Bugs of other colors die out in the forest (because they are eaten to extinction).

We now generalize this idea to prey that are fast or protected enough to avoid being eaten, predators that are strong or fast enough to still eat prey, ETC.